Electric switch



J. EATON ELECTRIC SWITCH May 8, 1945.

Filed June 5, 1943 Inventor: John Eaton,

Patented MayS, 1945 ELECTRIC SWITCH` y I John Eaton, Schenectady, N. Y.,assigner to General Electric Company, a corporation of `New YorkApplication .Tune 5, 1943, Serial No. 489,730

8 Claims.

My invention relates to electric switches, more particularly toelectromagnetically operated switches or contactors, and has for itsobject a 4contacter provided with simple and eecti-ve means forproducing a wiping action between the contacts, so as to increase thecurrent carrying capacity of the device.

In `carrying out my invention in onev form, l `.provide two springs forholding the movable contact in position on a support moved by anoperating coi1, Vthese two springs applying their forces at diii'erentpoints on the movable contact. The movable and stationary contactsurfaces are arranged angularly so that the movable contact rst touchesthe stationary contact at one edge thereby to elect yielding oi one ofthe springs and a normal rolling and wiping action on the stationarycontact, after which theiinal movement oi the armature to its attractedposition eiects further yieldingof the first spring and also yielding ofthe second spring to obtain an increased contact pressure.

f Preferably, the spring first to yield is relatively woah as odmparedwith a second spring, the Y magnetic pull applied to the armature atthat time'of initial contact not being strong enough to :nove theannature against the torce applied hy the second spring. Moreover thesecond spring applies to its forceA at an edge ci the movable contact.opposite the point oi initial contact engagement so as to-provide themanirnum leverage -to-loreak any weld between the two contacts at theinitial point of engagement.

More 'specifically I provide a relatively weak helical spring whichapplies a force at substantially the center of the movable Contact,

which spring yields iirst, and a relatively strong flat spring whichengages an outer edge of the movable contact remote from the initialpoint oiengagelnnt between' the two contacts.

For a more complete understanding oi my invention, reference should behad to the accompanying drawing, Fig. -1 of which-is a plan view partlyin `section of an electric switch embody- -ing my invention; Fig. Eis aview mainly in section taken alongthe line 2--2 of Fig. l lool:- ing inthe direction of'y the arrows; Fig. Bris a `sectional View taken alongthe line '3-3 of Fig. i

looking in the direction of the arrows; Fig 4 is a plan view of thearmature and movable contact mechanism; Fig. 5 is asectional view or"Fig. 4 looking in the direction of the arrowsi while Fig'. 6 lsafrontelevation view ol Figa showing one o! the springs. Referring tothe drawing, I have shown. my'

' magnet thearm|8.\ Y 1 It. will be noted that the springstrlp 2|' isprol invention in one form as comprising an operating coil I0 'providedwith a central magnet iron core member Il, end core pieces I2 and I3,anda iron armature I4 having one end pivoted at I5 on the end coremember I3. The armature I4 is biased to its unattracted position bymeans of a. helical tension spring I1. l

Secured to the armature I4 is a rigid switch arm I6'. Ihis switch armhas one end secured to the armature by means of rivets I9, the switchlarm and the rivet being electrically insulated from the armature bylayers of insulation i8 and' I8a and a cylindrical insulator 20surrounding the rivet. The switch arm extends at right angles to thedirection of movement of the armature, as shown, at right angles to thepivot axis of the armature.'

Also secured to the armature is a relatively strong spring strip 2lwhich has one end extending between the arm i6 and the layer ofinsulation It and secured to the armature by the rivets i9. This springextends along the switch arm but is bent away from the switch arm at anangle,`andits end has a' portion 22 bent at right angles toward theswitch' arm toa position in closely spaced relation with the side of theswitch.

arm at its end.

The switch arm carries a bridging contact member 23 made of electricallyconducting niaterial provided with contacts 24 and til at its ends for;engagementwith stationary contacts it and il. At its outer edge, i. e.the edge opposite the pivot of the armature, the bridging contact 'has'an extension 2B provided with a V shaped groove 2&3 which forms anelongated bearing seat for portions 3B and 3l on the e'nd of the vspringstrip 2l. It will be observed that portions 39 and 3i are spaced apartto form in elect an elongated hearing in the end of the spring 2l. i Gthe bridging contact is provided with two projections' 32 andv 33. Theseprotections are spaced along thelength of the contact arm in tween whichand the adjacent side of the bridging` contact is a vrelatively weakhelical com-4 .pression spring Bl. The pin 35 extends through anaperture Aprovided .for it' in the arm I6 and vis held in place by a pin38`extending through .its end and lying in a groove provided I orv it inAlso, on its side adjacent the arm vided with an enlarged openingthrough which extends the spring i1 and the pin 36, this openingdefining two bent arms 39 and 40 which are connected togetherat theirouter ends by the cross bar 4l.

The bridging contact member is put in place, the pin 33 being removed,by forcing its outer edge portion between the arm I6 and the spring 2|,the outer end of the spring 2| yielding somewhat thereby to seat theportions 30 and 3| on the end of the springlin the bearing groove 29. Itwill be observed that the spring 2| also by its engagement with thebearing 28 holds the bridging contact member 23 in transverse relationwith the switch arm. The projections 32 and p 33 hold the bridgingcontact in spaced relation with the arm. At this time the force appliedby the spring 2| to th bearing seatr 29 is sufiicient to. tilt theopposite side of the bridging contact away from the arm i6 about thepro.- jection 33`as a pivot. Next the pin 3G and' spring 31 are put inplace and the pressure of the spring 31 forces the inner edge of thebridging member oracle t tact, i. e., to the bearing seat 2Q, providesthe greatest possible leverage for the force of this spring in breakinga weld between the two contacts at their inner edges where engagement isiirst made, in the eventthat a weld is formed.

about the projection 33 as a pivot toward vthe arm i6 until theprojection 32 4rests onthe arm.

As seen in Figs. 2 and 3, the stationary contacts 26 and 21have theircontact surfaces disposed at a predetermined acute angle with thecontact faces on the bridging member. Consequently, when the coilisenergized and the armature moves the contact arm toward closed circuitposition, the inner edges of the movable contacts, i. e., the edgesadjacent the pivot of the armature, engage the stationary contacts rst.Thereupomas the armature moves toward its attracted position, the spring31 yields to allow the bridging contact to pivot at its outer edge onthe contact arm about the projection 33 in a clockwise direction as seenin Fig. 2. Also the movable contacts at the same time pivot clockwise onthe stationary contacts, producing a rolling and wiping action until thecontact faces are in parallel contact made engaging relation. Thearmature still is not quite in its fully attracted position and, incontinuing its movement to the final attracted position, it moves thearm i5 away :from the bridging member, which is now in. engagement withthe stationary contacts, thereby further compressing the spring 31 andbending the Stringer spring 2| In other words, the arm I6 moves awayfrom the outer end of the spring 2| which yields. Thus the bridgingcontact member ismaintained in engagement with the stationary contactsby the combined forces applied by the springs 2| and 31.

It will be observed that the bearing portions and 3| on the spring 2|are on opposite sidesof the end of the switch arm and are spaced asubstantial distance apart thereby to apply positive pressures to eachof the bridging contacts 2l the'helical spring 31.

lIt will be observed that the helical spring 31 applies its force atsubstantially the center of the bridging contact and, therefore, hasonly half the leverage with respect to the inner edge of the bridgingcontact, as compared with the iiat spring 2|. Moreover, of course,"theforce applied by the helical spring ls preferably much less than thatapplied by the hat spring 2i. Thus, in the event of a weld at theinitial point of engagement, the breaking of a weld and roll of thebridging contacts over the stationary contacts is assured by thestronger spring 2 The various parts of the switch are supported on twoparallel rectangular plates 42 and d3 made of electrically insulatingmaterial, such as a phenolic condensation product, each plate consistingof two layers, the inner layer being somewhat smaller than" the outerlayer and forming a Asupport for a iiexible strip covering member M,

preferably made of a brous insulating material. which with the two -sideplates encloses the operating parts of the device.`

These -two side plates are -held in fixed relation v 'with projections53 and 54 which extend through slots in the side plates. vSimilarprojections and 56 areA provided on the core member I3, whichprojections extend through apertures in the side members. Also, theapertures for the projections 55 and 56 are enlarged to receive theprojections 51 and 58 on-the armature thereby to hold the armature inplace with its lower edge, as seen in Fig. 2', pivoted on the left-handend of the core One advantage of the arrangement of the two springs sothat the force of one only is applied when the contacts first engage isthat the force applied to the armature follows roughly the maximum pullapplied' to the armature during its movement. It will be understoodthat, as the armvdzure moves toward its attracted position. the

In other words, the armature would not be actuated if it member I3.

i A stop cross bar 59 extending between the plates and secured to theplates by smaller end portions extending through openings in the platesis vprovided for the armature Il when in its unattracd position, asshown in Fig.' 2. A short bolt I0 extends toward the left, as seen inFig. 2, from the center of vthis bar 53 and extends loosely throughholes provided for it in the overlapping vends of the strip M and anouter cross bar 6|.

Thev outer cross bar E I is provided to secure the outer overlapping endof the flexible ilbre strip 44, the end of the strip being secured tothe cross-barby means of rivets 6|a, only one of which is shown. A nut62 on the bolt 60 holds across bar 5|- in place. Another cross bar 32ois' secured to the inner overlapping end of the strip 44 by means ofrivets. 'This cross bar 32a is similar in construction to the cross bar6|, and likewise has small ends mounted in slots in the outer edges ofthe side members 42 and I3.

Terminals 33 and 64 secured tothe side plates are provided for the endsI0. Also, similar of the operating coil While I have shown a particularembodiment of my invention, it will be understood, of course, that I donot wish to be limited thereto since many modifications may be made, andI there-v terminals 65 and 66 are prof kvided for the stationarycontacts. As shown in Fig. 3, the two stationary contacts aremountedfore contemplate by the appended claims to cover any suchmodiiications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

v1r. A switch comprising a switch member, means for moving said switchmember between open and closed circuit positions, a movable contactmovably mounted on said switch member,

a rst spring 'applying a force to said movable Contact therebyto biassaid movable contact against said switch member, a stationarycontactarranged to be engaged by said movablecontact when said switchmember is moved toward said closed circuit position, said stationarycontact having its contact surface at anangle with the contact surfaceof said movable contact so that edges of said contacts iirst engage eachother and said spring yields to provide a prev; liminary rolling actionof said movable contact on said stationary contact, and a second springapplying a force to the opposite edge of said movable contact to holdsaid, opposite edge againstsaid switch member during said rolling actionand yielding to apply an increased contact, maintaining force during apredetermined i'lnalA movement of said switch member to its closedcircuit position.

2. A switch comprising a pivoted switch arm, a movable contact movablymounted on the mov- .able other end of said switch arm. a rst springapplying' a force to said movable contact at sub'- stantially its centerthereby to bias said movable contact against said switch arm,v astationary contact arranged to be engaged by said movable contact whensaid switch arm is moved in one direction, said stationary contacthaving its contact surface at an angle with the contact surface of said,movable contact so that inner edges of said contacts adjacent the pivot`of said switch arm rst engage each other and said spring yields toprovide a preliminary rolling action of said movable contact about itsinner edge on said stationary contact and about its outer edge on said-contact arm to a :final contact made position,

and a second spring on said switch arm applying a force to said outeredge of said movable contact to hold said outer edge against said armduring said 'rolling action and yielding to apply an increased contactmaintaining force duringa predetermined final movement of said switcharm. if

3. A' switchcomprising a'switch arm, a movable contact mountedon themovable other end of said switch arm, a rst spring biasing said movablecontact against said switch arm. a bearingseat on an outer edge of saidmovable contact, a second spring secured to said arm at one i end andhaving its other end seated in said bearing seat, and a stationarycontactJ arranged to be engaged b'y said movable contact having itscontact surface atan angle with the contact surface of saidmovablecontactso that any edge oi' the said movable contact surface oppositesaid helical spring,

`.switch arm, an elongated bearing seat on one edge of saidbridgingcontact, a second spring secured to said switch arm at one endand having its other end transversely elongated and seated in saidbearing seat to hold said bridging contact in transverse relation withvsaid switch arm and apply a force to said one edge of said bridgingcontact -in the same direction as the force applied by said first springbut greater than the force applied by said rst spring, and stationarycontacts arranged to be engagedby said bridging contact, said stationarycontacts having their contact surfaces at an angle with the contactsurfaces on said bridging contact so that upon movement of said switcharm in one direction edges ci the latter contact surfaces opposite saidone edge engage said stationary contacts first thereby to provide arolling action and compression of said iirst spring and then compressionoi said second spring upon continued movement oi said switch arm.

5. a switch comprising a rigid switch arm, a pin secured to the movableend oi said switch arm extending at right angles with said switch armand in the direction of movement of said movable end. a movable contacton said movable end provided with a central aperture through which saidpin extends, a helical compression spring on said pin biasing saidmovable contact against said 4switch arm, a bearing seat on one edge ofsaid movable contact, a second spring having one other end seated insaid bearing seat to apply a force to said movable contact in the samedirection as said helical spring, said second spring applying c. greaterforcethan said and a stationary contact arranged to be engaged byy saidmovable Contact when said coil is energized, said stationary contacthaving its contact surface at an angle with the contact surface on ,saidmovable contact so thatupon movement of said. switch arm in onedirection an edge of the latter opposite said one edge ,en-

gages said stationary contact drst to provide a rolling action andcompression oi said helical spring and then yielding of said secondspring upon continued movement of said'switch ami.

6. A switch comprising a' switch a dat rst spring having one end securedtosaid switch' arm audits other end extending laterally atsubtion withsaid movable end, a contact membermounted on the movable end of saidarm, a bearing seat for the end'of said giirst spring on the outer edgeof said contact member whereby said first ,spring biases said outerejdge toward said arm, a second spring bearing on. said contact memberthereby to force said contact member about said rst spacing member to apredetermined spaced relation with said arm, a third spring for biasingsaid' switch arm to a predetermined circuit position, a stationarycontact having a. contact surface at an angle witha' contact surface onsaid contact member so that upon movement of said switch arm in onedirection the i ner edges of said surfaces engage each other rst therebycausing pivotal movement of said contact member on said arm against theforce applied by said second spring into parallel engaging relation withsaid stationary contact, and said 'contact arm being arranged to moveaway from said contact member during the final movement of said switcharm in said direction so that said movable contact member is heldagainst said stationary contact member by the forces applied of saidswitch arm to a position in closely spaced relation with said movableend, a Contact member mounted on the movable end of said arm,

a pair of spacing members between said Contact member and said armspaced apart along the length of said arm, a bearing seat for the end'of said first spring on the outer edge of said contact member wherebysaid first spring biases said outer edge toward said arm with theoutermost of said spacing members in engagement with said arm, a secondspring bearing on said contact member thereby to force said Contactmember about said rst spacing member to a predetermined spaced relationwith said arm determined by said second spacing member; a third springfor biasing said switch arm to a predetermined circuit position, astationary Contact having a contact surface. at a predetermined anglewith a contact surface on saidcontact member so that upon movement ofsaid switch arm to another position the inner vedges of said surfacesengage each other iirst thereby causing pivotal movement of said contactmember on said iirst spacing projection against the force applied bysaid second spring into parallel engaging relation with said stationaryContact, and said switch arm being arranged to move away from saidcontact member during the iinal movement of said switch arm to saidother position so that said movable contact member is held against saidstationary contact member by the forces applied by said iirst and secondsprings.

8. A switch comprising a switch arm, a first spring having one endsecured to said switch arm and extending along said switch arm with itsother end extending laterally at substantially right angles with the endof said switch arm to a position in closely spaced relation with the endof said switch arm, a bridging contact member mounted on said end ofsaid arm extending crosswise thereof, a pair of projections on saidbridging member at substantially its'v middle spaced apart along thelength of said arm, a bearing seat for the end of said iirst spring onthe outer edge of said bridging contact whereby said first spring biasessaid outer edge toward said arm with the outermost oi said projectionsin engageinent with said arm, a second spring bearing on said bridgingmember thereby to force the other of said projections into engagementwith said switch arm against the force applied by said first spring, athird spring for biasing said armature to its unattracted position andsaid switch arm to its open circuit position, spaced stationary contactsin position 'to be engaged by opposite ends of said bridging member whensaid switch arm' is moved in one direction toward a closed circuitposition, said stationary contact surfaces being positioned at an anglewith the contact surfaces on said bridging member so that the inneredges oi said surfaces engage each other .first thereby causing pivotalmovement of said bridging member on said outer projection against theforce applied by said sec-y ond spring for at engagement of said contactsurfaces, and said stationary contacts being positioned to provide formovement of said switch arm away from said bridging member against theforces applied by said first and second springs when said switch armmoves -to its final closed circuit position. JOHN EATON.

